Liquid rubbers are not a new class of materials: they are low molecular weight elastomers. Liquid rubbers can be prepared by a variety of polymerization mechanisms involving anionic, cationic, coordination, or free radical initiator systems and also by depolymerization of a high-molecular-weight polymer. Typical liquid rubbers have Mn of about 1,000 to about 10,000.
For a liquid diene rubber, e.g. liquid polybutadiene rubber (BR), a high level of unsaturation is present. Thus, it can be chemically modified in a variety of ways. The microstructure, molecular weight, and architecture of the liquid BR can affect its reactivity to certain types of chemical modification, the ability to introduce functional groups into the polymer, and potential application. In terms of commercial significance, maleinization, epoxidation, chlorination, and hydrosilation are probably the most important reactions.
Conventional techniques for terminating and thereby end functionalizing living polymers generally produce a single functional group per polymeric-chain end. And polymers with a limited number of chain-end functionalities are problematic in applications that are better served by polymers having chain ends with multiple functionalities. For instance, applications such as surface modification, coating and painting, adhesives, additives for polymer blends, and dispersing aids for fillers are better served by polymers having multiple functionalities per chain end. There is therefore a need in the art to provide polymers with chain-end moieties having multiple functional groups as well as a method for synthesizing such polymers.